We are developing nanoscale electronic circuits (nanofids) that will be implanted into millions of neurons to record neural activity during behavior. Our long-term goal is to record high-resolution neural activity information during acquisition and expression of learned behavioral models of addiction. The long-term health goal is to identify neuronal ensembles encoding addiction-related memories for eventual ablation. In this application, we are developing semiconductor chip prototypes that will transmit near-infrared (NIR) signals with unique frequency identification whenever intracellular calcium levels rise above a set threshold corresponding to neural activation. We are assessing power requirements and biocompatibility of the overall circuit and individual circuit components in air and intracellular model solutions. Signal attenuation of NIR output will be assessed in these solutions using NIR spectrometry. In future, the optimized circuit from this application will be incorporated into millions of devices that will be implanted into neurons for intracellular recordig of neural activity in brain during behavior.